Gas turbine plant



JUIYS, m@ W. H; ARMAcosT ET AL 2,404,938

GAS TURBINE PLANT Filed Feb.

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Wai-er, heater Patented July 30,- 1946 GAS TURBINE PLANT Wilbur H. Arniacost, Scarsdalc, and David M.

Schoenfeld, New York, N. Y., assignors to Combustion Engineering Company, Inc., New York,

Application February 10, 1945, Serial No. 577,245

3 Claims.

This invention relates to gas turbines and particularly to those in which the working fluid passes in heat exchange relationship with the gases and heating surface of a steam generating unit,

When employed with a steam generating unit the compressed working fluid for the gas turbine is heated indirectly by the products of combustion leaving the furnace of the steam generator. The products of combustion thereafter flow over various heating surfaces of the generator to be further cooled. Thus, the working fluid remains uncontaminated by impurities, such as ash, which would be present if it were made up, at least in part, of the products of combustion of a fuel. After leaving the heat exchanger, the working fluid is expanded through the turbine wherein it produces useful work and thereafter may be conducted back to the steam generating unit to there join with the products of combustion flowing through the generator.

An object of this invention is to provide an improved gas turbine including a steam generator.

In the drawing:

Figure 1 is a diagrammatic View of one form of the invention.

Figure 2 is a similar diagrammatic View of another form of the invention.

The drawing illustrates a steam generating unit comprising upper and lower drums I3, Ii connected by a bank of steam generating tubes I2 and an economizer I3 having tubes connected between inlet and outlet manifolds I4 and I5 all heated by a furnace I6 which is provided with a gaseous fuel burner I'I. Feed water is supplied through pipe 9 to manifold I4 and manifold I5 connects to the steam and water drum I3.

In Figure 1 a single heat exchanger 20 is shown having tubular elements suspended in the furnace and connected between inlet manifold 2l and out let manifold 22. In Fig. 2 there are two similar heat exchangers and 23, the first corresponding to that of Fig. 1 and the second having tubular elements suspended also within the furnace and connected between inlet and outlet mani folds 24 and 25.

In Figure 1 an air compressor 33, a gas turbine 32 and an electric generator 34 all have their respective shafts fastened together by couplings 34A so that the turbine serves as a common drive for all. Air enters compressor 3U through conduit 3I and leaves the compressor to ow through conduit 33 to a heat exchanger 35. From heat exchanger 35, the air flows through conduit 3I to inlet manifold 2I of heat exchanger 20 and from outlet manifold 22 through conduit 39 to gas turbine 32. From turbine 32 the air flows through the heat exchanger 35 and through conduit 3B to burner I'I. A branch 36 from conduit 38 delivers a portion of the air into the boiler setting to join the products of combustion flowing therethrough.

In Fig. 2 an air compressor having a first stage 33 and a second stage 30A, a gas turbine having 'a first stage 32 and a second stage 32A and an electric generator 34 all have their respective shafts coupled. Air enters compressor stage 30 through conduit 3l, is compressed, passes through intercooler 43 to second stage 30|A and thence through conduit 33 to a heat exchanger 35. From heat exchanger 35 the air flows through conduit 31 into inlet manifold 2| of heat exchanger 20, and from outlet manifold 22 through conduit 39 to stage 32 of the gas turbine. From stage 32 the air flows through conduit 4I into inlet manifold 24 of heat exchanger elements 23 and from its outlet manifold 25 through conduit 43 'to stage 32A of the gas turbine. From stage 32A the air flows through the heat exchanger 35 through conduit 38 and another heat exchanger 45 to vburner I'I. A branch 36 from conduit 38 delivers a portion of the air into the boiler setting to join the products of combustion flowing therethrough.

The feed water to the boiler enters through pipe 41 and divides, one portion flows through intercooler 43 to economizer inlet manifold I4, and thence into the steam and water drum Ii). The other portion flows through pipe 43 into heat exchanger 45. Upon leaving heat exchanger 45 the water divides, one portion flowing through pipe @il as hot water, for use other than in the boiler unit, and the other portion flows through pipe 5I to join the water leaving the economizer outlet manifold I5 flowing through the pipe to the steam and water drum I0.

In operation free air from compressors 30, 33A is delivered to heat exchanger 35 wherein it receives heat given up by the exhaust air from turbine stage 32, 32A, then flows through heat exchanger 2i) and is delivered to turbine stage 32. In expanding through the turbine 3'2, 32A it loses heat which is converted into work used for driving the compressor 30, 30A and electric generator 34. After leaving turbine stage 32, 32A the air is cooled within heat exchanger 35 to a temperature suitable for use in the fuel burning apparatus to which that portion necessary for combustion within the furnace is conducted. The remaining surplus portion of this air is delivered into the setting of the boiler unit, to join the products of combustion flowing through the unit, at a location where the products have been cooled to a temperature substantially that of the air.

According to the invention, heat exchanger 35 reclaims heat for use in the turbine from the exhaust of the air leaving the turbine in order to cool this air to a temperature suitable for use in the fuel burning apparatus. Heretofore this air was cooled by a heat exchanger through which cooling water was passed, and the discharged hot water was in part or Wholly Wasted, resulting in loss of heat from the combined turboboiler unit.

According to the invention there is a further thermal saving incurred by delivering the surplus portion oi the air leaving heat exchanger 35 into the boiler setting through conduit 36 at a location where the products of combustion have been cooled to substantially the air temperature. Heretofore the surplus air was delivered into the lurnace and therein mixed with the products of combustion. This procedure resulted in lowering the temperature of the products leaving the furnace, and a lower temperature difference between the products and heat absorbing tubes of boiler and economizer. Although the How of products through the tubes was increased, the net result was a loss in the heat transferred to boiler and economizer. However', by introducing the surplus air according to the invention the products of combustion `are undiluted up to the point within the lboiler setting where the surplus air is introduced and a net gain in overall heat absorption by the unit from the products and the surplus air results. Another advantage in using heat exchanger 35 in the manner described is that it may be made ol' relatively inexpensive materials, since it is exposed to low temperatures, when compared to the costly materials used in heat exchanger 2li, which is subjected to high temperatures. Since heater 35 assumes some of the air heating otherwise done by heater 20, the latter may be smaller thereby incurring a further saving in cost and proportionately also overcomes the objection of the removal of the dint and slag deposits on the larger heater within the furnace which cause a variation in the heated air temperatures.

Further, in the form shown in Fig. 2, that portion of the air leaving heat exchanger 35 which is conducted to the burner ll is further cooled by water flowing in indirect relation to the air in heater 45. The cooling water is taken from the boiler feed water supply pipe 4l', conducted through heater 5 and thence conducted by pipe il to join the water leaving economizer outlet manifold l5 t0 flow into steam and Watel drum ll. Should the water required by the economizer I3, intercooler 40 and heater 45 exceed the demand of the boiler It, the surplus may flow through pipe 56 for outside use. However, by this arrangement of using the relatively cold water for supplying heater 45, the temperature of the surplus water is kept to a. minimum incurring a minimum heat loss from the unit.

, What we claim is:

2 l; In a power plant having a gas turbine, a uid compressor and a steam generator unit including an associated furnace, fuel burner and a setting for confining the flow of the products of combustion therethrough; first and second iluid heaters for heating the compressed uid; conduits for conveying compressed fluid from the compressor to the first heater, from the first to the second heater, from the second heater to the turbine, from the turbine exhaust to rst heater in out of contact relation to the compressed fluid flowing therethrough thereby cooling said exhausted fluid, and from the second heater to the burner, said last conduit having a branch delivering a portion of the fluid into the setting at a location Where theproducts of combustion have been cooled to substantially the same temperature of the delivered fluid.

2. In a power plant having a gas turbine, a fluid compressor and a steam generator unit including an associated furnace, fuel burner and a setting for confining the flow of the products of combustion therethrough; rst and second fluid heaters for heating the compressed fluid; and a third heat exchanger for cooling the fluid; conduits for conveying compressed liuid from the compressor to the first heater, from the first to the second heater, from the second heater to the turbine, from the turbine exhaust to first heater in out of contact relation to the compressed liuid flowing therethrough thereby cooling said exhausted fluid, and from the second heater to the third heat exchanger and thence to the burner, said last conduit having a branch in advance of the third heater, with respect to the fluid flow, delivering a portion of the fluid into the setting at a location where the products of combustion have been cooled to substantially the same temperature of the delivered fluid; a feed Water pipe and a branch pipe from the feed Water pipe to the steam generator to the third heat exchanger for cooling the uid flowing therethrough in out of contact relation; a pipe from the third heat exchanger to the steam generator, and a surplus Water pipe connected into the pipe from the third heat exchanger.

3. In a power plant having a gas turbine, a fluid compressor and a steam generator unit including an associated furnace, fuel burner and a setting for confining the ow of the products of combustion therethrough; rst and second fluid heaters for'heating the compressed fluid; and a third heat exchanger for cooling the fluid, conduits for conveying compressed fluid from the compressor to the first heater, from the first to the second heater, from the second heater to the turbine, from the turbine exhaust to first heater in out of contact relation to the compressed iiuid flowing therethrough thereby cooling said exhausted fluid, and from the second heater to the third heat exchanger and thence to the burner, said last conduit having a branch in advance of the third heater, with respect to the fluid flow, delivering a portion of the fluid into the setting at a location Where the products of combustion have been cooled to substantially the same temperature of the delivered fluid; a feed water pipe and a branch pipe from the feed water pipe to the steam generator to the third heat exchanger for cooling the uid flowing therethrough in out of contact relation; an economizer; the feed water pipe being connected to the economizer and hot water pipe from the economizer to the steam generator; a pipe from the third heat exchanger to the hot water pipe leaving the economizer, and a surplus water pipe connected into the pipe from the third heat exchanger.

WILBUR H. vARMACOSTl DAVID M. SCHOENFELD. 

